Vehicle running board construction

ABSTRACT

An improved vehicle running board construction and method of making same including a hollow metal support pipe with an elongated mid-section step portion adapted in vehicle-mounted orientation to extend generally parallel to and adjacent a sill of a vehicle door that provides access to a passenger or freight compartment of the vehicle. An elongate mounting opening is formed in an upwardly facing exterior surface area of the pipe mid-section. A support plate has a plurality of transverse trusses arranged in spaced apart relation in a longitudinally extending row and straddling the opening side edges and resting thereon for support. A plurality of spacer webs are individually interposed between and joined to longitudinally adjacent pairs of the trusses and support at each of their longitudinally opposite ends, a resilient spring finger catch oriented to underlie an associated one of the pipe opening side edges. Each finger catch has a free end resiliently engaging an interior surface of the pipe for holding the step plate against upward release from the pipe. A step plate is mounted on and covers the support plate as well as the mounting opening of the pipe. The step plate has a generally flat planar central step tread portion with an undersurface bearing upon the support plate trusses. The step plate also has downwardly extending side flanges respectively extending outwardly of and downwardly past the pipe opening side edges and terminating at free end edges that preferably resiliently engage the exterior surface of the pipe. A plurality of retaining barbs extend downwardly from the step plate undersurface into snap lock tang engagement with associated receiving slot anchor tabs provided in the trusses for holding the step plate on the support plate, and vice versa.

FIELD OF THE INVENTION

This invention relates to automotive vehicle running boardconstructions, and more particularly to heavy duty tubular or bent-pipetype running boards or similar exterior mounted steps currently in useon various sport utility and pick-up truck type automotive vehicles.

BACKGROUND OF THE INVENTION

The wide spread popularity in recent years of pick-up trucks and sportutility vehicles for both on-road and off-road use in business,recreational as well as everyday travel has popularized the “rugged”styling of such vehicles, as well as their accessories, from both thepractical as well as aesthetic standpoint. Thus the exterior runningboard construction provided for such vehicles, both as originalequipment and after-market accessory type products, has seen the adventof a simple large tubular support, typically in the form of a two orthree inch diameter steel pipe bent-formed at its opposite axial endsfor connection to the undercarriage of the vehicle. A straight runcentral portion of the pipe is typically positioned outboard of andbelow the door sill of the cab of the pick-up truck or the front and/orrear doors of a sport utility vehicle (SUV). Such pipe running boardsprovide both the rugged strength and structural support required forsuch use, and are also resistant to damage from traveling throughunderbrush as well as from various other types of misuse encountered inthe typical service life of such vehicles. Also, since the pipe isspaced outboard of the vehicle body metal it is easy to clean off, as bya hose-down, mud clinging to the surface of the pipe and to the stepcarried by the pipe.

Although the use of a simple pipe in and of itself has been proposed andmarketed with some success, safety considerations require that a stepplate of some type be mounted on top of the pipe and provided with aribbed, corrugated or other contoured gripping pattern on its upperface. This insures safe and secure footing by users of the running boardboth during entry and departure from the vehicle passenger space, aswell as when riding in a standing position on the running board.Hitherto, such a pipe and step plate running board construction has beenprovided by mounting a step plate, made as a plastic extrusion, onto theopposed edges of an upper cut-off section of a metal support pipe. Thestep plate was supported along its longitudinal center line by support asupport beam in the form of a piece of untreated pine wood boardinserted into the metal pipe. The board rested along its bottomlongitudinal edge on the bottom interior of the pipe and was dimensionedso that its upper longitudinal edge abutted the underside of the plasticextrusion step plate. However, this arrangement tended to become looseand disassembled from use and abuse under normal wear and tearconditions, as well as from swelling of the wood support from watercollecting in the pipe. Thus, this prior commercial construction did notprovide a fully secure mounting of the step plate on the pipe and hencecould be pried off during running through heavy brush or similar extremebut not unusual conditions encountered during the off-road use of suchvehicles. Accordingly, it has been previously proposed (but not producedor reduced to practice) to provide a step plate/pipe running boardconstruction in which the wood interior brace is replaced by aninjection molded plastic member spanning the length and width of theinterior of the pipe beneath the slotted portion of the pipe to serve asan insert support structure for a separately manufactured step plate tobe mounted thereon. However, this proposed design presented problems asto its mounting assembly into a straight pipe section in order tocapture the support member within the pipe, and involved an expensiveand impractical procedure for assembly. Hence, this design was abandonedas being not satisfactory at least from the standpoint of securemounting, ruggedness and/or economy of manufacture and assembly.

OBJECTS OF THE INVENTION

Accordingly, among the objects of the present invention are to providean improved running board construction for installation and use onautomotive vehicles such as pick-up trucks, SUVs and similar typevehicles wherein the aforementioned tubular pipe-type running board isemployed in combination with an improved support plate member and animproved step plate member, and wherein the latter two members may bemolded each as a one-piece member from plastic materials, wherein thestep plate may be mounted to the support plate as a sub-assembly withoutuse of separate fastening members and yet securely and reliablythereafter retained as a unitary sub-assembly, and wherein the stepplate/support plate sub-assembly may be easily and securely mounted onthe support pipe in a rapid and reliable manner, again without the useof separate fastening members.

Another object is to provide an improved running board construction ofthe aforementioned character that, once mounted on the running boardpipe, provides a rugged and secure mount thereto that is able towithstand abuse, damage and resist pry-off removal from striking underbrush and other similar forces, that is easily cleaned, that is massproducible by conventional injection molding processes and can be madein recyclable materials that are weather and moisture resistant and ableto withstand the extremes of outdoor temperature conditions from dessertto arctic temperatures, that provides a safe, rattle-free, andsqueak-proof standing platform mounted on the tubular pipe support andthat has a long and useful service life, that is easily repairable andthat is economical in construction and reliable in operation.

SUMMARY OF THE INVENTION

In general, by way of summary description and not by way of limitation,the invention accomplishes the foregoing and other objects by providingan improved vehicle running board construction comprising theaforementioned hollow metal support pipe adapted to be secured to avehicle exterior at first and second longitudinally opposite ends of thepipe. The elongated mid-section step portion of the pipe is adapted invehicle-mounted orientation to extend generally parallel to and adjacenta sill of a vehicle door that provides access to a passenger or freightcompartment of the vehicle. An elongate mounting opening is formed in anupwardly facing exterior surface area of the pipe mid-section as definedby first and second laterally opposite and longitudinally extendingopening side edges both lying in a plane chordally intersecting an upperradial cross sectional segment of the pipe. This opening is defined atopposite longitudinal ends thereof by first and second divergentlyinclined end edges each extending from the opening side edges to ajunction with an uppermost apex area of the upwardly facing exteriorsurface area of said pipe.

The running board construction also includes a support plate having aplurality of transverse trusses arranged in spaced apart relation in alongitudinally extending row and straddling said opening side edges andresting thereon for support.

The support plate also has a plurality of spacer webs individuallyinterposed between and joined to longitudinally adjacent pairs of thetrusses. Each of these webs has, at each of the longitudinally oppositeends thereof, a resilient spring finger catch oriented to underlie anassociated one of the pipe opening side edges. Each finger catch has afree end resiliently engaging an interior surface of the pipe forholding said step plate against upward release from the pipe.

The running board construction further includes a step plate mounted onand covering the support plate as well as the mounting opening of thepipe. The step plate has a generally flat planar central step treadportion with an undersurface bearing upon the support plate trusses. Thestep plate also has first and second downwardly extending side flangesrespectively extending outwardly of and downwardly past the first andsecond pipe opening side edges. These flanges each terminate at a freeend edge that preferably resiliently engages the exterior surface of thepipe. A plurality of retaining barbs extend downwardly from the stepplate undersurface into snap lock tang engagement with associatedreceiving slot anchor tabs provided in the trusses for holding the stepplate on the support plate, and vice versa.

Preferably each support plate truss has a planar top wall extendinglengthwise perpendicular to the longitudinal dimension of the pipe, thetruss top walls being co-planar with one another. Each of the trusseshas a pair of sidewalls, one dependent from the leading and one from thetrailing edges of each truss top wall. The spacer webs preferably eachcomprise a planar member extending in a plane parallel to the truss topwalls and spaced therebelow. The opposite forward and trailing edges ofeach web wall are joined to the lower edges of the mutually adjacenttruss sidewalls of a mutually longitudinally adjacent pair of thetrusses.

Preferably each spring finger catch comprises a V-shaped member lying ina plane perpendicular to the longitudinal axis of the pipe. Each catchhas a first leg that is integrally joined at its upper end to the endedge of an associated one of the spacer web walls and extends downwardlyto a vertex of the V of the spring leg catch. Each catch also has asecond leg extending upwardly and outwardly at an acute angle to thefirst leg from a junction at such vertex with the first leg, andterminates in a free end edge that forms the free end of the springfinger catch.

Preferably the support plate trusses, spacer webs and resilient springfinger catches are all integrally joined together by being injectionmolded with the support plate as a one-piece part, preferably fromrecyclable high strength thermoplastic material such as a polycarbonate.

Likewise, preferably the step plate side flanges and step plateretaining barbs are all integrally joined together by being injectionmolded with the step plate as a one-piece part, again perferably from ahigh strength recyclable plastic material such as thermoplastpolyosalene containing some synthetic rubber material.

The invention also includes a method of constructing the vehicle runningboard construction that includes the steps of forming a sub-assembly ofthe plates by assembling the step plate onto the support plate byrelatively moving said plates bodily toward one another whilemaintaining their respective longitudinal axes generally parallel untilthe retaining barbs have fully snap lock engaged the truss anchor tabs.Then an assembly of the support pipe with the sub-assembly is formed byrelatively moving the sub-assembly and pipe bodily toward one anotherwith the leading and trailing ends of the sub-assembly and pipe openingaligned and while maintaining their respective longitudinal axesgenerally parallel until the free ends of the catch second legs havebeen slid past the pipe opening edges and into the interior of the pipeand the step plate side flanges resiliently engage the exterior surfaceof the pipe.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing as well as other objects, features and advantages of thepresent invention will become apparent from the following detaileddescription of the best mode presently known to the inventor of makingand using the invention, from the appended claims, and from theaccompanying drawings (which are to engineering scale unless otherwiseindicated) wherein:

FIG. 1 is a perspective view of a current model pick-up truckillustrating one preferred embodiment of a running board construction ofthe invention mounted to the underside of the vehicle and extendingoutboard of and adjacent the sill edge of the driver-side door of thetruck cab.

FIG. 2 is a fragmentary perspective view illustrating the mid-sectionstraight-length portion of the support pipe of the running boardconstruction of the invention embodiment of FIG. 1 with a stepplate/support plate sub-assembly mounted thereon.

FIG. 3 is an exploded perspective view of the components shown in FIG. 2illustrating the step plate disposed above the underlying support platewhich in turn is shown disposed above the elongated mounting openingprovided in the upper surface of the pipe mid-section.

FIG. 4 is a fragmentary top plan view of the step plate of the assemblyof FIGS. 1, 2 and 3.

FIG. 5 is a fragmentary side elevational view of the step plate of FIG.4.

FIG. 6 is a fragmentary bottom plan view of the step plate of FIGS. 4and 5.

FIG. 7 is an end elevational view of the trailing end of the step plate,i.e., the right hand end as viewed in FIG. 5.

FIGS. 8 and 9 are cross-sectional views taken respectively on the lines8—8 and 9—9 of FIG. 4.

FIG. 10 is a fragmentary top plan view of the support plate componentshown by itself.

FIG. 11 is a fragmentary side elevational view of the support plate ofFIG. 10 shown by itself.

FIG. 12 is an end elevational view of the trailing end of the supportplate, i.e., the right hand end as viewed in FIGS. 10 and 11.

FIG. 13 is a fragmentary bottom plan view of the support plate of FIGS.10-12.

FIGS. 14 and 15 are cross-sectional views taken respectively on thelines 14—14 and 15—15 of FIG. 11.

FIG. 16 is a fragmentary side elevational view of a portion of themid-section of the support pipe of the running board construction shownin FIGS. 1-3, but shown by itself.

FIG. 17 is a fragmentary top plan view taken on the line 17—17 of FIG.16.

FIG. 18 is a cross-sectional view taken on the line 18—18 of FIG. 16,and FIG. 19 is a cross-sectional view taken on the line 19—19 of theexploded view of FIG. 3 but showing the parts non-exploded in assembledrelation as in FIG. 2.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Referring generally to FIG. 1, a current model pick-up truck 20 is shownwith a preferred but exemplary embodiment of a pipe-type running boardconstruction 22 of the invention mounted to the underframe of thevehicle and positioned for use as a running board for the driver-sidedoor 24 of the truck cab 26. The running board construction 22 comprisesa hollow support pipe 28 having bent-formed opposite longitudinal ends30 and 32 respectively that extend beneath the vehicle and are mountedin a conventional manner to the vehicle frame. Pipe 28 has a generallystraight mid-section portion 34 extending between ends 30 and 32 thatsupports a step plate/support plate sub-assembly 36 provided inaccordance with the invention.

As best seen in FIG. 3, the step plate/support plate sub-assembly 36 ismade up of two one-piece molded plastic components, namely a step plate38 that is snap-tang-lock mounted on a support plate 40 that in turn issnap-spring-finger-catch installed in an elongated mounting opening 42(FIGS. 3 and 16-18) provided in the upwardly facing approximately 90°circumferential surface area of pipe mid-section 34.

Support pipe 28, by way of preferred example, may be a hollow stainlesssteel pipe section having an outside diameter of about three inches anda wall thickness of one sixteenth inch. Alternatively, the pipe may bemade of a suitably aluminum alloy material. In a typical installationthe axial or longitudinal dimension of the mid-section 34 of pipe 28 mayrun from six to sixty inches, depending upon the vehicle application.The mounting opening 42 in pipe mid-section 34 is defined by pair ofparallel, longitudinally extending and laterally opposite side edges 44and 46 (FIGS. 3 and 16-18) that lie in an imaginary horizontal (in-useorientation) cut plane P (perpendicular to the plane of the drawing inFIG. 18) disposed approximately half way between the horizontal centerline C/L of tube section 34 (FIG. 18) and the apex A of the uppermostsurface area of the complete circular section of pipe section 34 (FIGS.16 and 17). The opposite ends of mounting opening 42 are defined by cutplanes E₁ and E₂ (FIG. 16) that extend perpendicular to the plane of thedrawing in FIG. 16. The end cut planes E₁ and E₂ thus respectively formthe elliptical curved end edges 50 and 52 (FIGS. 3 and 17)characteristic of the intersection of a plane intersecting a cylinder atan acute angle to the cylinder axis.

Step plate 38 is preferably made as a one-piece injection molded partfrom a suitable recyclable high strength, high melting pointthermoplastic material, such as thermoplast polyosalene, and preferablycontaining some suitable synthetic rubber material. Plate 38 has anappropriate lengthwise dimension parallel to its longitudinal axis sothat when mounted to pipe mid-section 34 the opposite longitudinal ends60 and 62 of plate 38 axially overlap and cover the end edges 50 and 52respectively of opening 42 (FIG. 2). As best seen in FIG. 19, plate 38has an inverted U-shape in transverse cross section as defined by atread platform or deck portion 64 provided with a peripherallyencircling dependent side edge flange 80. Deck 64 has a smoothundersurface 66 bearing on the upper surface of support plate 40. Deck64 has a suitable tread configuration on its upper surface made up ofparallel longitudinally extending ribs 68 that alternate with grooves 70to provide good footing or traction to a person standing on step plate38. Preferably the friction grip of the deck upper surface is furtherenhanced by providing a conventional acid etched stipple grain finish onthis surface. The ribs 68 and grooves 70 terminate at their oppositelongitudinal ends at the bases slightly inclined smooth forward and aft(i.e., leading and trailing) deck areas 72 and 74 that are each inclinedupwardly from the major plane of platform at a slight angle, say 10°, asbest seen in FIG. 8. As best seen in FIGS. 4 and 6, these inclined enddeck areas 72 and 74 in plan view are generally bullet-nose shaped sothat the overall configuration of plate 38 is generally canoe-shaped inplan view.

The downwardly dependent flange 80 integral with platform 64 and enddeck portions 72 and 74 surrounds substantially the entire outerperiphery of these portions of plate 38. Flange 80 thus has an outboardportion 82 integral with the outboard edge of platform 64, and aninboard (closest to vehicle) flange 84 integral with the inboard edge ofplatform 64. As best seen in FIG. 19, the lower free end edges 86 and 88of flange portions 82 and 84 are preferably designed such that, whenstep plate 38 is in assembly with pipe 28 and support plate 40, theseedges yieldably and resiliently engage the outer surface of pipe section34 at approximately the horizontal mid-plane thereof. Thus, the moldedfree-state condition of flange portions 82 and 84 has a span distanceslightly less than the chordal dimension of pipe 34 at the engagementpoints of tips 86 and 88 so that the flanges 82 and 84 are resilientlycammed apart during installation and retain a tight embracing andgenerally water tight fit with the outer surface of pipe section 34.

Flange 80 in the portions 90 and 92 thereof contiguous with the inclinedend platform portions 72 and 74 respectively terminate in a lower edge94 and 96 (FIGS. 5, 6 and 8) that is inclined upwardly from the junctionwith lower edges 86 and 88 at oppositely inclined angles generallymatching the angles of inclination of cut planes E₁ and E₂ that definethe end edges 50 and 52 of opening 42.

The underside of step plate 38 is provided with a plurality of lockingtangs preferably arranged, as best seen in FIGS. 6, 7,8 and 9, in alongitudinally extending inboard row of tangs 100, 102, 104, 106, 108,110 and a longitudinally extending outboard row of tangs 112, 114, 116,118, 120 and 122 that protrude integrally downwardly from the platform64 of plate 38. Each locking tang 100-122, as best seen in FIGS. 7, 9and 19, is provided with a leading end having an inclined cammingsurface 124 extending divergently back toward platform surface 66 andterminating in a locking ledge or shoulder 126 (FIG. 19), and functionsas described in more detail hereinafter. Similar but slightly longercentrally located forward and aft locking tangs 130 and 132 depend fromthe fore and aft end platforms 72 and 74 and are likewise configuredwith an inclined leading camming surface terminating in a lockingshoulder surface that is generally parallel to the undersurface 64 ofplate 38.

The construction and details of support plate 40 are best seen in FIGS.3 and 10-15 as well as in FIG. 19. Support plate 40 is preferably madeas a one-piece molded part, preferably injection molded from a suitablerecyclable plastic material such as a high strength, high melting pointpolycarbonate material, and includes a plurality of weight-load bearingtruss means that in the disclosed example total ten in number. Thesetruss means are individually identified by truss reference numerals 140,142, 144, 146, 148, 150, 152, 154, 156 and 158 in FIG. 3, are arrangedin a longitudinally extending row and are equally longitudinally spacedfrom one another. Each of these trusses 140-158 is identical inconstruction and configuration and hence the forward-most or leadingtruss 140 will only be described in detail. Truss 140 comprises a planartop wall 160 of rectangular configuration in plan view (FIG. 10) andhaving a smooth, flat planar upper surface 162 (FIGS. 10-12 and 19), andlongitudinally opposite ends 164 and 166 that are spaced apart asuitable distance so as to extend in assembly with pipe 28 beyond pipeopening edges 44 and 46 as shown in FIG. 19. Each truss section 140-158also has a pair of laterally spaced downwardly divergent sidewalls 170and 172 (FIGS. 10, 11 and 14) that provide vertical load bearing andbending-stress-resistant supports for top wall 160. The bottom surfaceof wall 160 is a stepped configuration symmetrical about thelongitudinal center line of plate 40 (FIGS. 11, 13, 15 and 19) made upof ledge supporting surfaces 174 and 176 that bear upon pipe openingedges 44 and 46 respectively (FIG. 19). Ledge surfaces 174 and 176 areinwardly bounded by shoulder portions 178 and 180 that help restrainsliding motion of plate 40 on edges 44 and 46 in a directionperpendicular to the pipe axis. Reinforcing gussets 182 and 184 are alsoprovided between shoulder 178 and the adjacent side surfaces of thetruss bottom wall that extend downwardly to the plane of the major flatbottom wall surface 186 of truss section 140 (FIGS. 13 and 19).Corresponding gussets 188 and 190 are provided at the oppositelongitudinal end of truss section 140. These gussets help brace supportledges 164/176 and 166/174 since the truss sidewalls 170 and 172 do notunderlie these ledges but rather terminate flush with the outer edges ofthe major bottom surface 186.

Each truss section 140 also has a pair of tang-receiving throughopenings 192 and 194 of rectangular cross section (FIG. 10), eachinboard side of which has a locking lug 196 and 198 respectivelyprotruding into the opening and configured in vertical cross section, asbest seen in FIG. 19, to cooperate with the associated tang 100-122 ofstep plate 38 to form a one-way catch construction for holding stepplate 38 on support plate 40 in assembled relation. The undersurface ofeach truss is also provided with four rectangular pockets 200, 202, 204and 206 (FIG. 13) to reduce weight and material in each truss section,leaving an intervening cruciform rib pattern for increasing thestrength-to-weight ratio of the truss section. Likewise, the uppersurface 162 of each truss is provided with a pair of weight-reducingrectangular pockets 208 and 210 adjacent each of the tang throughopenings 192 and 194 respectively, and also leaving a rib therebetween.

Each of the truss sections 140-158 that laterally span pipe opening 42in assembly therewith is spaced from its longitudinally adjacent trusssection(s) and integrally connected thereto by the associated one of aplurality of web walls 220, 222, 224, 226, 228, 230, 232, 234 and 236(FIG. 3). Each of these web walls 220-236 is integrally joined along itsside edges to the bottom of the flanking sidewalls 170 and 172 of themutually adjacent pair of truss sections 140-158. In addition to servingas a longitudinal spacer between truss sections, each web wall 220-236adds further lateral stiffness and structural modulus to the supportplate 40, by imparting a corrugated overall configuration to the supportplate in vertical cross section along the longitudinal axis of the same.In addition, each web wall 220 provides support for a pair of V-shapedspring catches 240 and 242 integrally joined one to each of the oppositelongitudinal ends of each web wall 220-236.

The construction of spring catches 240, 242 is shown in FIGS. 10-15 and19. It will be seen that the inboard leg 244 of catch 240, and thecorresponding mirror image inboard leg 246 of catch 242 (FIG. 14), isintegrally joined at its upper edge to the respective end edge of theassociated web wall 220, 222, etc. so that the catches are cantileversupported therefrom. (“Integral” as used herein means joined together orunited by being molded in one piece). The free end edges 248 and 250 ofthe outboard legs 252 and 254 of catches 240 and 242 respectively (FIG.14) are spaced apart from one another in their free-state condition adistance slightly greater than the span between the end edges 164 and166 of top wall 160 of each truss section. The vertex of each springcatch 240, 242 is provided with a downwardly pointing V-shaped entranceprotrusion 256, 258 respectively (FIGS. 15 and 19) to provide a“lead-in” extension of the tapering entrance surface to facilitatedownward insertion assembly of support plate 40 into opening 42 of pipesection 34.

Each of the opposite longitudinal ends of support plate 40 isconstructed with a symmetrical mirror image configuration providinglongitudinal leading and tailing end anchoring tabs 260 and 262extending longitudinally from longitudinally opposite end truss portionsof the support plate (FIG. 3). A top wall 264 (FIG. 10) of each of thetabs 260 and 262 extends from the free end of the tab toward the body ofplate 40 to a junction with a transverse dependent wall 172 joined toanother web wall 266, in the case of forward tab 264, and in the case ofaft or rearward tab 262, to a sidewall 170 joined to a web wall 268 inturn joined to the sidewall 172 of truss 158 (FIG. 10). Each of the endstabs 260, 262 has generally, in transverse cross section, aninverted-U-shape as defined by sidewalls 270 and 272 (FIGS. 11, 12 and13) that continue across associated web wall 266 and 268 to formreinforcing struts between the associated cross walls 170 and 172 (FIG.10). Each end tab 260, 262 is provided with a through slot 274 and 276respectively that respectively receive the central catch-tang 130 and132 (dependent from step plate 38 as described previously) when stepplate 38 is assembled to support plate 40 to form the initial stepplate/support plate sub-assembly 36 (FIG. 3).

The opposite longitudinal ends of support plate 40 are furtherreinforced by a pair of stiffening ribs 278 and 280 (FIGS. 10-15 and19). The forward stiffening rib 278 extends along the central verticalplane of support plate 40 beneath front tab 260 (FIGS. 11 and 13), andback to the forward sidewall 170 of truss 144. The upper edge of rib 270is flush with the top surface plane of support plate 40 throughout thelength of the rib, and likewise protrudes below the plane of the webwalls beneath the support plate 40. The rear stiffening rib 280 isconstructed in like manner and symmetrically to rib 278 and thecorresponding associated structure of the support plate 40.

Assembly Procedure

As indicated previously, step plate 38 is injection molded as aone-piece part separately from the remaining components, and preferablylikewise as to support plate 40. Preferably, step plate 38 isconstructed such that flange 80 is semi-resilient and hence somewhatpliable. Hence when support plate 40 is inserted bodily into step plate38, with its then respective axes oriented longitudinal parallel, to theoutboard free end edges 248 and 250 of the spring catches of supportplate 40 can be inserted past the bottom edges 86 and 88 of the sideflanges 82 and 84 while these flanges are suitable fixture-held flexedapart to facilitate passage of the catch-finger free ends. Preferablythis is done on a suitable assembly jig so that the locking tangs100-122 are axially aligned with their associated tang-receivingopenings 192, 194 in support plate 40. Also, this sub-assembly procedureis preferably performed while step plate 38 is still at an elevatedtemperature following de-molding so as to take advantage of the greatersoftness and flexibility of the flanges while reaching final cure androom temperature conditions.

As the inclined leading surface of each tang 100-122 engages theinclined surface of the locking tabs 196 and 198 in each of theassociated openings 192 and 194, the respective locking tangs will becammed or wedge-forced so as to flex to thereby permit passage of thebarb of the locking tang past the locking barbs or lugs 196, 198 of theassociated tang-receiving opening in the support plate. As the bottomsurface 66 of the step plate seats on the upper surfaces 162 of thesupport plate, the tangs 100-122 will snap into catch relationship withlugs 194 and 196 in a one-way locking-tang-catch relationship. Hence,step plate 38 cannot be pulled apart from support plate 40 merely byexerting separation forces on these two parts, short of exerting adestructive force capable of shearing the locking tangs and/or lugs.After assembly of the support plate to the step plate to form thesub-assembly 36, and release from the assembly fixtures, the sideflanges 82 and 84 return to their original as-molded free-statecondition.

The step plate/support plate sub-assembly 36 is assembled to the runningboard pipe 28 by aligning the front and rear ends 60 and 62 of stepplate 38 with the front and rear ends of pipe opening 42 in axiallyoverlapping relationship therewith. The registry of the parts forvertical lateral bodily insertion of the sub-assembly 36 into theopening 42 is done by aligning the forward edge of an abutment tab 300(FIGS. 6 and 8), which depends from the undersurface of forward platform72 forward of leading edge of tang 130, with the apex of the leadingedge 50 of opening 42. Likewise, the trailing edge of another abutmentlug 302, that depends from platform 74 of step plate 38 adjacent lockingtang 132, is aligned with the apex of the trailing edge 52 of opening42. Then sub-assembly 36 is loaded onto and into pipe opening 42 bymoving it bodily, preferably with its longitudinal axis orientedparallel to that of pipe section 34, in a direction perpendicular to thelongitudinal axes of these components. This relative assembly motioninitially engages the outer surfaces of the spring legs 252 and 254 ofspring catches 240 and 242 with the side edges 46 and 44 respectively ofopening 42. This will laterally center the sub-assembly with its axisaligned vertically with the axis of the pipe section (when oriented asin FIG. 19). When such initial contact is made, it will be seen fromFIG. 19 that the lower free end edges 86 and 88 of the side flanges 82and 84 of the step plate 38 are spaced slightly outboard of the exteriorsurface of pipe section 34, respectively being disposed radiallyoutwardly and overlapping the opening edges 44 and 46. Hence, as jigassembly force is exerted on pipe section 34, opposing the assemblyforce being exerted on sub-assembly 36, to move the two major componentstoward one another, the spring catches 240 and 242 will flex in the freelegs 252 and 254 in the inboard legs 244 and 246 and also about thecantilever integral junction with the associated web wall. This permitsthe pipe opening edges 44 and 46 to slide along the surfaces of theoutboard legs of the spring catches until the free ends 248, 250 thereofclear these pipe opening edges 44 and 46. The leg free ends 248, 250then slidably engage the interior surface of the pipe section 34.

During this assembly motion the free edges 86 and 88 of flexible flanges82 and 84 initially strike the exterior surface of pipe section 34approximately in the zone thereof aligned with the spring catch outboardleg free ends 248 and 250 when in final assembled relationship, as inFIG. 19. Then during the completion of the assembly motion of the majorcomponents together to the assembled position of these components inFIG. 19 the curvature of the pipe section cams the free ends 86 and 88of flanges 82 and 84 mutually apart to thereby resiliently stress thesame so that they tightly resiliently engage the pipe surface as theyreach their final assembled position shown in FIG. 19. In this conditionthe fore and aft relative motion of the sub-assembly 36 relative to pipesection 34 is limited by the abutments 300 and 302 respectively strikingthe associated apices of the pipe opening end edges 50 and 52. Thislongitudinal range of shifting may be on the order of say one eighth ofan inch, whereas the overlap of the ends 60 and 62 of step plate 38relative to the apices of opening end edges 50 and 52 is a matter of sayone half inch or so.

The semi-resilient nature of the spring legs 240 and 242 renders themrelatively stiff springs which require significant assembly force eventhough assembly is facilitated by the camming angle provided by theV-shape of the spring catches. Retrograde or removal motion of thesub-assembly 36 from pipe section 34 is therefore strongly resisted bythe geometry and construction of the spring catches relative to thecurvature of the pipe, and the difference in the radial dimension of theopening edges 44 and 46 from the pipe center line relative to thesimilar dimension of the free end edges of the outboard legs of thespring catches, i.e., a substantial amount of interference for thisessentially one-way interference insertion assembly mode.

It thus will be seen in the mass production set-up for an automotiveparts manufacturer, suitable assembly jigs (not shown) can be relativelysimple and yet perform the two-step assembly operation in rapidsequence. The one-way locking tangs integrally dependent from theunderside of step plate 38 provide a very strong and secure one-waycatch with an associated support plate 40 so that the resultantsub-assembly 36 can be handled as such reliably without danger ofcomponent separation in the manufacturing process. Likewise, whensub-assembly 36 is drop-in, snap-engaged assembled with running boardpipe 28, there is again a snap-in one-way type engagement that isreadily accomplished rapidly and reliably and yet provides arattle-proof, squeak-free and secure fit and spring-stressed retentionof these components one with another during adverse usage and over anextended service life in use.

Due to the one-way locking tangs between step plate 38 and support plate40 on the one hand, and the one-way resilient spring-finger engagementbetween support plate 40 and the running board pipe section 34 on theother hand, fitting together in assembly and retention thereafter of thefinished assembly components is accomplished without the use ofextraneous or separate fastening members such as screws, bolts or thelike. However, if desired, such separate fastening members, whether theybe conventional threaded fasteners, pop rivets, blind rivets, etc. canbe employed to secure step plate 38 onto support plate 40, either inaddition to or in lieu of the locking tangs 100-122 and 130 and 132.

It will be understood that the lengthwise dimension of step plate 38 andthe corresponding dimension of support plate 40 can be varied to suitthe application requirements and the length of the straight section 34of the running board pipe 28. It is also to be understood that in someapplications two or more pairs of locking tangs 100-122 of the stepplate 38 can be omitted from the row of pairs of locking tabs betweenthe opposite extremes in the row, if desired to reduce molding andmaterial costs. Also, for larger length sizes of step plate 38, thesupport plate 40 alternatively can be made up of two or more sectionsmolded successively from a single shorter length mold cavity in order toeconomize on mold cost. These sections then are held in longitudinalend-to-end abutment by their respective snap engagement with associatedstep plate tangs 100-122.

It also will be apparent from the foregoing description to those skilledin the art that the running board construction as described hereinabovewith reference to the accompanying drawings fully and amply fulfills theaforestated objects of the invention. The running board construction ofthe invention also provides many advantages over the aforementionedprior art constructions in terms of stronger more reliable assembly andrattle-proof and squeak-free operation, extended service life, ease ofassembly, economy of manufacture, weatherproof durability of materials,absence of extraneous or separate fastening members, pleasing aestheticand appearance qualities, and good traction and footing for boarding andunboarding of the vehicle as well as standing on the running board whilethe vehicle is standing still or traveling.

Indeed, in a test of a working prototype constructed pursuant to theembodiment described and illustrated hereinabove the failure modeoccurred under a statically applied solitary weight loading of about1300-1400 psi, thereby greatly exceeding the initial design criteria offailure at about 300 psi applied at any given point on the step plate.The running board construction of the invention has thus been proven tohave a high strength-to-weight ratio achieved at a very low cost.

It is also to be understood that support plate 40 can be first molded asa separate piece and then used as an insert in a mold cavity designedfor overmolding step plate 38 onto support plate 40 in order to makesub-assembly 36.

What is claimed is:
 1. A vehicle running board construction comprising in combination a hollow support step pipe adapted to be secured to a vehicle exterior at first and second longitudinally opposite ends of said pipe, said pipe having an elongated mid-section step portion adapted in vehicle-mounted orientation to extend generally parallel to and adjacent a sill of a vehicle door that provides access to a passenger or freight compartment of the vehicle, said pipe mid-section having an elongate mounting opening formed in an upwardly facing exterior surface area thereof and defined by first and second laterally opposite and longitudinally extending opening side edges both lying in a plane chordally intersecting an upper radial cross sectional segment of said pipe, said opening being defined at opposite longitudinal ends thereof by first and second end edges each extending from said opening side edges to a junction with an uppermost apex area of said upwardly facing exterior surface area of said pipe, a support plate having a plurality of truss means straddling said opening side edges and resting thereon for support, a plurality of spacer web means individually interposed between and joined to longitudinally adjacent pairs of said truss means, each of said web means having at each longitudinally opposite end thereof a resilient spring finger catch underlying an associated one of said pipe opening side edges and having a free end resiliently engaging an interior surface of said pipe for holding said step plate against upward release from said pipe, and a step plate mounted on and covering said support plate and said mounting opening of said pipe, said step plate having a generally flat planar central step tread portion having an undersurface bearing upon said support plate truss means, said step plate also having first and second downwardly extending side flanges respectively extending outwardly of and downwardly past said first and second pipe opening side edges and each terminating at a free end edge resiliently engaging the exterior surface of said pipe, and fastening means securing said step plate onto said support plate.
 2. The combination of claim 1 wherein said fastening means comprises a plurality of retaining barbs extending downwardly from said step plate undersurface into snap lock tang engagement with associated receiving slot anchor tabs provided in said truss means for holding said step plate on said support plate.
 3. The combination of claim 1 wherein each of said support plate truss means has a planar top wall extending lengthwise perpendicular to the longitudinal dimension of said pipe, said truss means top walls being co-planar with one another, and wherein each of said truss means has a pair of sidewalls, one dependent from the leading and one from the trailing edges of said truss means top wall, and wherein each said web means comprises a planar member extending in a plane parallel to said truss means top walls and spaced therebelow, the opposite forward and trailing edges of each said web wall being joined to the lower edges of the mutually adjacent sidewalls of a mutually longitudinally adjacent pair of said truss means.
 4. The combination set forth in claim 3 wherein each said spring finger catch comprises a V-shaped member lying in a plane perpendicular to the longitudinal axis of said pipe and having a first leg integrally joined at its upper end to the end edge of an associated one of said web walls, said first leg extending downwardly to a vertex of said V of said spring leg catch, said V-shaped spring finger catch having a second leg extending from a junction at said vertex with said first leg upwardly and outwardly at an acute angle to said first leg and terminating in a free end edge defining said free end of said spring finger catch.
 5. The combination set forth in claim 4 wherein said support plate plurality of truss means, said support plate spacer web means and said resilient spring finger catches are all integrally joined together by being molded with said support plate as a one-piece part.
 6. The combination set forth in claim 5 wherein said support plate is injection molded from plastic material comprising a high strength, high melting point polycarbonate.
 7. The combination set forth in claim 6 wherein said step plate side flanges and said step plate retaining barbs are all integrally joined together by being molded with said step plate as a one-piece part.
 8. The combination set forth in claim 7 wherein said step plate is formed by being injection molded from plastic material comprising a high strength, high melting point thermoplast polyosalene material.
 9. The combination set forth in claim 1 wherein said first and second end edges of said opening in said support pipe are respectively defined by cut planes inclined at a shallow angle upwardly relative to the longitudinal axis of said pipe and extend in oppositely divergent directions at the respectively axially opposite ends of said opening, and wherein said step plate has bullet-nose shaped end platforms at each of the axially opposite longitudinal ends thereof inclined to conform to the cut plane of the end edges of said pipe opening and covering the same in assembly.
 10. The combination set forth in claim 9 wherein said step plate is formed with a longitudinally extending and laterally alternating row of grooves and ridges to form a tread pattern thereon.
 11. The combination set forth in claim 9 wherein said side flanges of said step plate comprise a portion of and are integrally joined to a single flange of said plate encircling the entire periphery thereof and resiliently sealably engaging the exterior surface of said pipe in surrounding relation to the entirety of said edges of said pipe opening.
 12. The combination set forth in claim 3 wherein said support plate has leading and trailing tab portions having snap-tang engagement with the underside of said step plate and being disposed in assembly below the apex of said end edges of the associated end of said pipe opening, said step plate having first and second stop abutments protruding from the underside thereof adapted to abuttingly engage the apex of the adjacent said first and second end edges of said opening to limit movement of the sub-assembly of said step plate and said support pipe longitudinally relative to said pipe.
 13. The combination set forth in claim 4 wherein each of said spring finger catches has a protrusion extending downwardly from said vertex and oriented to provide an extension thereof to thereby assist lead-in entry assembly of said support plate into and past the side edges of said pipe opening during assembly thereinto.
 14. The combination set forth in claim 13 wherein said support plate has fore and aft stiffening ribs integrally joined thereto and protruding downwardly from the underside thereof and extending upwardly to a flush relationship with the upper surface of said top walls of said truss means, each said rib extending with its major plane parallel to the axis of said pipe and perpendicular to the plane of said top walls of said support pipe, each said rib also extending beneath an associated one of said end tabs and toward the longitudinal center of said step plate so as to span at least two of said truss means.
 15. A method of constructing a vehicle running board construction comprising the steps of: (1) providing a hollow support step pipe adapted to be secured to a vehicle exterior at first and second longitudinally opposite ends of said pipe, said pipe having an elongated mid-section step portion adapted in vehicle-mounted orientation to extend generally parallel to and adjacent a sill of a vehicle door that provides access to a passenger or freight compartment of the vehicle, (2) forming in said pipe mid-section an elongate mounting opening in an upwardly facing exterior surface area thereof and defined by first and second laterally opposite and longitudinally extending opening side edges both lying in a plane chordally intersecting an upper radial cross sectional segment of said pipe, said opening being defined at opposite longitudinal ends thereof by first and second end edges each extending from said opening side edges to a junction with an uppermost apex area of said upwardly facing exterior surface area of said pipe, (3) providing a support plate having a plurality of truss means dimensioned for straddling said opening side edges and resting thereon for support, and also having a plurality of spacer web means individually interposed between and joined to longitudinally adjacent pairs of said truss means, each of said web means having at each longitudinally opposite end thereof a resilient spring finger catch adapted for underlying an associated one of said pipe opening side edges when in assembly therewith and having a free end adapted for resiliently engaging an interior surface of said pipe for holding said step plate against upward release from said pipe when in assembly therewith, (4) providing a step plate adapted to be mounted on and cover said support plate and said mounting opening of said pipe when in assembly therewith, said step plate having a generally flat planar central step tread portion having an undersurface adapted to bear upon said support plate truss means when in assembly therewith, said step plate also having first and second downwardly extending side flanges adapted to respectively extend outwardly of and downwardly past said first and second pipe opening side edges when in assembly therewith, and each said side flange terminating at a free end edge adapted to resiliently engage the exterior surface of said pipe when in assembly therewith, (5) providing fastening means for securing said step plate onto said support plate, comprising a plurality of retaining barbs extending downwardly from said step plate undersurface adapted for snap lock tang engagement with associated receiving slot anchor tabs provided in said truss means for holding said step plate subassembly on said support plate, (6) forming a sub-assembly of said plates by assembling said step plate onto said support plate by relatively moving said plates bodily toward one another while maintaining their respective longitudinal axes generally parallel until said retaining barbs have fully snap lock engaged said truss means anchor tabs, and (7) forming an assembly of said support pipe with said sub-assembly by relatively moving said sub-assembly and said pipe bodily toward one another with the leading and trailing ends of said sub-assembly and said pipe opening aligned and while maintaining their respective longitudinal axes generally parallel until said free ends of said second legs of said spring catches have been slid past said first and second pipe opening edges and into the interior of said pipe and said step plate side flanges resiliently engage the exterior surface of said pipe. 